nothing but water and air, flowered and produced 
seeds to perfect maturity. From these facts, and 
some others, he infers that, “in many conditions, 
certain plants are apt to draw from the azote in 
the air;’ and he adds, “ but in what circum- 
stances and in what state azote fixes itself in 
vegetables, isas yet unknown tous. Indeed, azote 
can enter. directly into plants, if their green parts 
are fit to fix it. Azote, too, can be conveyed into 
vegetables by water, which is always aerated, 
and which is always taken up by the roots. In 
short, it is possible, as many physicians think, 
that it exists in the air in very sinall quantities 
of ammoniacal vapour.” M. Boussingault is thus 
as vacillating and doubtful as to the form in 
which the azote enters plants, as he is certain 
respecting the fact of their obtaining it from the 
atmosphere; and while he commences his very 
brief statement on the subject by seeming to as- 
sert that they extract it from atmospheric air, 
he terminates with the suggestion that they pos- 
sibly receive it under the form of ammoniacal 
gas. Yet no evidence whatever exists that plants 
can assimilate nitrogen from atmospheric air, 
while very satisfactory evidence has been exhib- 
ited by Liebig, and tested by other eminent 
chemists, that they very readily obtain it from 
ammoniacal gas in the atmosphere, not alone by 
the suffusion of that gas around them, but also 
and chiefly by its descent to their leaves and 
roots in a state of solution in rain-water. Who- 
ever peruses our article on Ammonia, and assents 
to the doctrines which it advocates, will have 
scarcely a doubt that most, and very probably 
all, of the nitrogen fixed by the clover and the 
pease in M. Boussingault’s experiments, was ob- 
tained from ammonia held in commixture with 
the atmosphere. 
Dr. Liebig, indeed, assumes such high ground 
-as to assert that all the nitrogen of plants, in all 
circumstances whatever, is obtained in the form 
of ammonia,—that, when brought into contact 
with them in the soil in any other form, it com- 
bines with hydrogen to constitute ammonia be- 
fore being available tou them,—and that in the 
case of fertilizing by the use of nitrates, a doubt 
305 
side in the base of the salt rather than ia the 
nitrogen of its nitric acid; and, in reference to 
plants obtaining nitrogen from the atmosphere, 
he says, “ Plants, as we know, grow perfectly well 
in a mixture of charcoal and earth, previously 
calcined, if supplied at the same time with rain- 
water. Rain-water can contain nitrogen only in 
three forms, as dissolved atmospheric air, as 
nitric acid, or as ammonia. Now, the nitrogen 
of the air cannot be made to enter into combina- 
tion with any element except oxygen, even by 
the employment of the most powerful chemical 
means. We have not the slightest reason for 
believing that the nitrogen of the atmosphere 
takes part in the process of assimilation of plants 
and animals; on the contrary, we know that 
many plants emit the nitrogen which is absorbed 
by their roots, either in the gaseous form, or in 
solution in water. But there are, on the other 
hand, numerous facts, showing that the forma- 
tion in plants of substances containing nitrogen, 
such as gluten, takes place in proportion to the 
quantity of this element conveyed to their roots 
in the state of ammonia, derived from the putre- 
faction of animal matter.” The conclusion which 
Dr. Liebig afterwards attempts to found upon 
other premises, that plants receive the whole of 
their nitrogen in the form of ammonia, appears 
to us, and has appeared to far abler judges, to be 
hasty and ill-reasoned; yet no reasonable doubt 
can exist that most or all plants receive their 
chief supply of nitrogen in the ammoniacal form. 
This, for all the practical purposes of agriculture 
or of gardening, is the whole drift of the ques- 
tion of nitrogen,—the grand and momentous fact 
which challenges the cultivator’s attention; and 
with this fact before them, our readers will do 
well to give a very careful perusal to our article 
on Ammonia.—Turner’s Elements of Chemistry.— 
Ure’s Dictionary of Chemisiry.—Thomson’s Sys- 
tem of Chemistry —Davy’s Agriculiural Chemistry. 
—ILnebig’s Chemistry of Agriculture. — Boussin- 
gaut’s Rural Economy.—Chaptal’s Chemistry ap- 
plied to Agriculture—Johnston’s Lectures on Agri- 
cultural Ohemistry.—M. Dumas in the Philosophi- 
eal Magazine.—Dr. Madden in Quarterly Journal 
is due whether the fertilizing power may not re- | of Agriculture—Edinburgh New Phil. Journal. 
| 
